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Open Access
Further screening of Venda medicinal plants for activity against HIV type 1 reverse transcriptase and integrase
(2006-03-15) Bessong, Pascal O.; Rojas, Luis B; Obi, Larry C.; Tshisikhawe, Peter M.; Igunbor, Eunice O.
The use of medicinal plants for AIDS-related conditions is common in South Africa. In order to establish an antiviral rationale for the use of these plants we screened fractions of the methanol extracts of medicinal plants for activity against HIV-1 reverse transcriptase (RT) and integrase (IN). The n-butanol fraction obtained from the crude methanol extracts of the roots of Bridelia micrantha (Hochst) Baill. (Euphorbiaceae) was observed to be as the most active inhibiting the RNA-dependent-DNA polymerization (RDDP) activity of HIV-1 RT with an IC50 of 7.3 g/ml. However, it had no activity on the 3’-end processing activity of HIV integrase. Bioassay-guided fractionation of the n-butanol fraction yielded friedelin and -sistosterol, which did not inhibit the RDDP of RT or 3’-end processing functions of IN even at a concentration of 500 M. An uncharacterized fraction obtained in the bioassay-guided fractionating process inhibited the RDDP with an IC50 of 9.6 g/ml, but had no inhibition on IN. Phytochemical screening indicated the presence of flavonoids and tannins in the uncharacterized fraction.
Open Access
Rural Small, Medium and Micro Enterprises And Role of Local Economic Development Agencies in the Vhembe District, Limpopo Province
(2006-09-16) Matloga, Selokela Reginald; Musyoki, A.
Small, Medium and Micro Enterprises (SMME) are vital factors in the economy of less developed countries. It has been a major source of employment, motive force for local economic development and poverty alleviation in developing countries including South Africa. It is agreed world wide that strong SMMEs give a country strong economic growth. In South Africa, SMMEs are not strong especially in rural areas, which comprise mainly of emerging SMMEs owned by Africans. There are hosts of institutions in South Africa which are active in the development of rural SMMEs. Local Economic Development Agencies (LEDAs) in the study areas are engaged in helping rural SMMEs to flourish. However, rural SMMEs are still facing many problems and are unable to flourish. This research is aimed at evaluating Local Economic Development (LED) support on local rural SMMEs in the study area in order to advance feasible strategies for support to enhance rural SMME's growth from the survival stage. Social survey methods involving interview schedules were used, providing descriptive and analytic data. The qualitative and quantitative data was analysed using an SPSS programme. The research findings indicate that LED support in the study area is failing to enhance rural SMME growth. The support does not cover the entire business requirement necessary for rural SMME growth. The study therefore advances strategies for LED support, which would be effective enough to enhance rural SMME growth and sustainability.
Metadata only
In-vitro bioactivity of fractions from a local medicinal plant on HIV-1 replication, and selected fungal and bacterial pathogens
(2009-03) Mutshembele, Awelani Mirinda; Bessong, Pascal O.; Eloff, Jacobus N.; Obi, Larry
Open Access
Drug Resistance Mutations in Naive HIV-1 South African Patients, and Construction of Molecular Clones to Phenotype Putative Resistance Mutations
(2009-03) Mavhandu, Lufuno Grace; Bessong, P. O.; Rekosh, David; Hammarskjold, Marie-Louise
In countries such as South Africa where access to therapy is progressing data is required on patterns of resistance and evolution of resistance. Thirty protease (PR) and 31 reverse transcriptase (RT) amino acid sequences of HIV primary isolates from drug naNe patients from rural settings in South Africa were examined for resistance mutations. Samples were collected between May and August 2007. Phylogenetic analysis showed that all the sequences were HIV-1 subtype C in both the protease and reverse transcriptase genes. The mean genetic distances among the sequences were 0.0170-0.0786 for the protease, and 0.0045-0.0890 for the reverse transcriptase. However, it was noted that 3 pairs of samples 07VGNF5ZA and 07VGNF6ZA, 07VGNF7ZA and 07VGNF8ZA, 07VGNF10ZA and 07VGNF13ZA did not show any genetic variability among their protease sequences. No major resistance mutation was observed among the protease sequences. However, the following minor resistance mutations were noted: L101N (3/30), A71T (1/30), and T74S (2/30). Examination of the reverse transcriptase gene for resistance mutations reveal the presence of V118I (1/30), V179D (1/30), K103N (2/30). Most of the RT sequences were wild-type, although V118I (3.3%) and k103N (6.7%) associated with resistance to lamivudine and nevirapine, respectively, were observed. In summary, this study has shown that most of the viruses in Limpopo Province, representing the northeastern part of South Africa are HIV-1 subtype C, and that the prevalence of resistant mutations among the drug na"fve patients is still low. Although combination antiretroviral therapy has resulted in a considerable improvement in the treatment of human immunodeficiency virus type 1 (HIV-1) infection, the emergence of resistant virus is a significant obstacle to the effective management of HIV infection and AIDS. Systems to be used in the testing of phenotypic drug resistance and susceptibility are being developed. These may intimately be used in guiding therapy to improve long term suppression of HIV replication. Two proviral chimeric clones making use of pMJ4 and pNL4-3, and two vector plasmids which deletions of sequences encoding HIV-1 protease or reverse transcriptase were constructed for cloning of HIV-1 PCR products. Growth of constructs was monitored by p24 antigen production. Susceptibility to protease and reverse transcriptase inhibitors was measured by using resistance test vectors that contain a Luciferase indicator gene. Cells were co-transfected with packaging plasmids, pluc, and pEnv, resulting in the production of virus particles that were used to infect target cells. Luciferase activity was measured following a single round of replication. The chimeric constructs MJ4 carrying the NL4-3 Apal-Hpal cassette (MJ4/NL4-3) and NL4-3 carrying the MJ4 Apal-Hpal cassette (NL4-3/MJ4) were successfully developed as shown by restriction digestion analysis. Considering growth of the constructed chimeras NL4-3/MJ4 was better than MJ4/NL4-3 although not robustly. Good p24 production was obtained from all four gap-pol plasmids. MJ4/NL4-3 worked better in delivering luciferase to the target cells while NL4-3/ML4 appeared totally devoid of any infectivity. The vectors pCMVGagPol(MJ4)-RREr and pCMVGagPol(NL4.3)-RREr were created and both expressed the viral gag-pol protein. Viral inhibition test showed that the vectors can be inhibited by NRTI, NNRTI and Pl. Inhibition was seen in all drugs in different concentrations indicating that the system works. The results showed that vector systems constructed can be used to evaluate putative drug resistant mutations, coding for resistance to protease and reverse transcriptase inhibitors, detecte� in patient viruses. In addition, the system can also be used to evaluate candidate drugs and assist in the development of new drugs that are active against resistant HIV-1 virus.
Open Access
q- Enumeration of permutations avoiding adjacent patterns
(2009-09) Takalani, Ntendeni Annah; Tshifhumulo, T. A.
Open Access
Detection of Cryptosporidium species in stools of HIV/AIDS patients in Bela-Bela, South Africa
(2010-06) Makuwa, Stenly Modupi; Bessong, P. O.; Samie, A.; Potgieter, N.
Open Access
Mapping ecological zones in the Kruger National Park using remote sensing
(2010-08) Ratshibvumo, Thihanedzwi; Munyati, C.; Ogola, J. S.
Fuel wood energy is the energy that is extracted from wood materials this includes - branches, stems, twigs and stems. The energy harnessed in this source is used for different purposes in Maraxwe area this include: cooking, heating, warming, lighting, brick burning or hardening, pot making or pottery and other activities. Due to many activities attached to one and the same source, severity of effects on fuel wood resources increases. The study therefore is undertaken to investigate into rural fuel wood energy crisis in Maraxwe village, and to come up with different alternative sources of energy. It will also alert people on their utilization, extraction, rate and depletion on fuel wood. Through this they will be aware and participate in ways to mitigate the problems. The outcomes of the research will therefore clearly identify or describe the problem, assess factors that affect fuel wood energy and resources thus coming up with strategies to solve the problem sustainable. The crisis has caused many socio-economic as well as ecological problems in the local community and their environment. According to the study the problem has-been identified and there is a need for solutions to mitigate the crisis. After interviewing local community members and representative leader a potential solution was derived at- namely the use of biogas was suggested as better alternative source of energy (capable of mitigating the crisis).
Open Access
The population ecology of Securidaca longepedunculata Fresen. in the Nylsvley Nature Reserve, Limpopo Province, South Africa
(Fyton, 2012) Tshisikhawe, M. P.; Baloyi, O.; Ligavha-Mbelengwa, M. H.; Bhat, R. B.
Securidaca longepedunculata Fresen., commonly known as the violet tree, belongs to the family Polygalaceae. It is widely distributed in tropical Africa, Mozambique, as well as in the North- West and Limpopo provinces of South Africa. The Vhavenda people use the roots of this species as an aphrodisiac. The species is co-dominant in the savanna vegetation of the Nylsvley Nature Reserve. This research looked at the ecology of the study species within the Nylsvley Nature Reserve because of its importance there. Understanding the population structure and environmental factors that impact on the species might help in assessing the population in urban areas. The population of the study species in the reserve displayed an adequate growth curve, when looking at its stem circumference and height-size classes. High intensity fires showed a negative effect on individuals of S. longepedunculata. Evidence of animals feeding on the roots at the study species was also recorded in the study.
Open Access
Flood Frequency Analysis of Annual Maximum Stream Flows for Luvuvhu River Catchment, Limpopo Province, South Africa
(2012) Singo, L. R.; Kundu, P. M.; Odiyo, J. O.; Mathivha, F. I.; Nkuna, T. R.
Luvuvhu River Catchment (LRC) is one of the regions in South Africa where floods have caused enormous damage and impacted negatively on fauna and flora. Over the years, the catchment has experienced floods resulting from heavy rainfall associated with the ITCZ. Annual maximum flow data from 8 stations with 50 years hydrological data were used to analyze flood frequencies in the catchment. To derive the probability of occurrence of flood events, the frequency distributions which could best describe the past characteristics and magnitudes of such floods were tested. This involved the determination of the best flood frequency models, which could be fitted to the available historical recorded data. The distribution models used included the Generalized Extreme Value, Gumbel or Extreme Value type 1, Log-Normal and the Log Pearson type III distributions. The extreme value analysis showed that the Gumbel and Log Pearson type III distributions provided the best fit.
Open Access
Invasive alien plant species: A case study of their use in the Thulamela Local Municipality, Limpopo Province, South Africa
(Academic Journals, 2012-07-19) Semenya, Sebua S.; Tshisikhawe, Milingoni P.; Potgieter, Martin T.
The spread of plants from one country to another through intentional and unintentional human activities is a serious threat to the world’s biodiversity; second only to habitat destruction. However, a number of studies have shown that invasive alien plant species can positively contribute to rural economies. This paper is an attempt to document a few of these species ‘positive contribution to rural inhabitants’ well-being in and around Thulamela Local Municipality in Vhembe District of South Africa. Information on the uses of invasive alien plant species were obtained in 2010 through interviews with local inhabitants and traditional healers. Twenty one plant species, from 15 families, were found to be utilized by rural inhabitants. These species are important sources of food and medicine, provide firewood, and are of aesthetic value. They have become alternative sources of utilization, where the indigenous vegetation has been decimated by overexploitation. This study postulates that their extensive use, under careful management, could form part of a strategy for social upliftment and environmental management in poor rural municipalities.
Open Access
Medicinal utilization of exotic plants by Bapedi traditional healers to treat human ailments in Limpopo province, South Africa
(Elsevier Ireland Ltd., 2012-10-13) Semenya, Sebua S.; Potgieter, Martin; Tshisikhawe, Milingoni P.; Shava, Soul; Maroyi, Alfred
Ethnopharmacological relevance: Most exotic plants are usually labelled as alien invasives and targeted for eradication. However, some of these exotic plants play an important role in the traditional primary healthcare sector of the Bapedi culture in the Limpopo Province of South Africa. The medicinal uses of most of these species have neither been documented nor their biological activity evaluated. Aim of the study: To make an inventory of exotic species employed by Bapedi traditional healers to treat different human ailments in the Limpopo Province, South Africa. Materials and methods: Semi-structured interviews, observation and guided field walks with 52 traditional healers were employed to obtain ethnobotanical data during first half of 2011 on the use of exotic plant species by Bapedi healers to treat human ailments. Based on ethnobotanical information provided by these healers, specimens were collected, numbered, pressed, and dried for identification. Results: A total of 35 exotics species belonging to 21 families and 34 genera, mostly from the Fabaceae and Solanaceae (11.4% for each), Apocynaceae and Asteraceae (8.5% for each) were used by Bapedi healers to treat 20 human ailments. Trees (45.7%) and herbs (37.1%) are the primary source of medicinal plants. Species most frequently reported were used for the treatment of hypertension (35%), diabetes mellitus, erectile dysfunction and gonorrhoea (25% for each). The highest consensus from individual accounts of the traditional healers on the use of exotic plant remedies in this study was noted for the three ailments. These were for Catharanthus roseus (gonorrhoea, 60%), Punica granatum (diarrhoea, 38.4%) and Ricinus communis (sores, 21.5%). Of the 35 exotic plant species recorded, 34.2% are regulated by the Conservation of Agricultural Resources Act (1983) (CARA) No. 43 of 1983 either as worst weeds or invaders. Conclusion: The present study demonstrated that exotic plant species play an important part as medicinal remedies employed by Bapedi healers to treat different human diseases in the Limpopo Province. The use of these species as alternative sources of medicinal remedies could alleviate harvesting pressure of wild indigenous plants, thereby enhance biodiversity’s region. However, there is a need to formulate an appropriate policy to retain some of the useful medicinal exotics (listed under CARA No. 43 of 1983) within the environment before their medicinal value vanishes as they are eradicated through management strategies adopted by the South African government.
Open Access
An evaluation of the extent and threat of bark harvesting of medicinal plant species in the Venda Region, Limpopo Province, South Africa
(2012-11-11) Tshisikhawe, M. P.; van Rooyen, M. W.; Bhat, R. B.
The medicinal flora of the Venda region consists of a variety of species, which may potentially provide therapeutic agents to treat different diseases. Bark use for medicinal purposes has been reported for approximately 30% of the woody species (153 species) in the Venda region in southern Africa. However, only 58 plant species are commonly harvested for the medicinal properties in their bark and found in muthi shops in the region. These 58 species were scored for the possible threat of bark harvesting to the plant survival. Ethnobotanical studies indicate that the growing trade in indigenous medicinal plants in South Africa is posing a threat to the conservation and preservation of many plant species. Apart from pharmaceutical companies, trade in medicinal plants has become a way of making a living for some people. This study investigated the pattern of trade in medicinal plants by local markets in the Venda region, Limpopo Province, South Africa. Indications are that bark harvesting may threaten some of the plant species.
Open Access
Population biology of Brackenridgea zanguebarica in the presence of harvesting
(Academica Journals, 2012-12-03) Tshisikhawe, Milingoni P.; Van Rooyen, Margaretha W.
Population biology studies play a major role in understanding the ecology of our highly utilized natural resources. Intense and frequent harvesting of bark from species with a high market demand often result in ring-barking of trees. The trees subsequently die, and the species becomes rare over time. Brackenridgea zanguebarica Oliv. is a species in demand not only because of its medicinal value but also because it is highly regarded for its magical value. The species has a limited distribution and is found only at Thengwe in the whole of South Africa. The population structure of the species was investigated and the response of the species to harvesting pressure evaluated in order to gain an understanding of its survival strategies. In spite of the high demand for the species it seems to be surviving the harvesting pressure. B. zanguebarica showed a healthy population structure with lots of seedlings. The adult individuals showed a very high degree of bark regeneration as a response to bark removal from medicine men. The inverse J-shaped curve showed that the population is healthy although sharp decreases between stem diameter size classes were observed. Fewer older individuals have healthy crown covers since crown health status tends to decrease with increase in stem diameter. It is therefore important to monitor the diameter size classes that are being impacted negatively by medicinal bark harvesting for the population to remain viable at all times.
Open Access
Analysis of the solar radiation data and the determination of regression coeffients for Vhembe Region, Limpopo Province
(2012-12-11) Mulaudzi, Tshimangadzo Sophie; Sankaran, V.; Lysko, M. D.
An attempt has been made to determine the regression coefficients from sunshine hours for the Vhembe Region, Limpopo Province. Parameters such as horizontal average daily extraterrestrial solar radiation (H0) and daily possible sunshine hours (N) were computed. Horizontal average daily global radiation data and daily actual sunshine hour data for the five stations in this study were obtained from Agricultural Research Council (ARC) and South African Weather Services (SAWS). The plots of monthly average daily relative sunshine hours t0 ) versus clearness index(.!!...) were N Ho drawn to determine the values of a and b of Angstrom - Prescott linear equation (where N,, and H represent the actual sunshine hours (in hours) and global solar radiation on the horizontal surface (in MJ) respectively. The variables a and b are the regression coefficients. The results obtained are discussed. From the computations, the values of a and b for Vhembe Region are calculated and the results obtained are compared with the regression coefficients for different countries. The regression coefficients from a station with the best correlation of the coefficients were used to compute the estimated average monthly horizontal global solar radiation for the other four stations and the results compare favourably with our data.
Open Access
Genetic characterization of human immunodeficiency virus from Northern South Africa
(2012-12-19) Iweriebor, Benson Chuks; Bessong, Pascal Obong; Mphahlele, Jeffrey; Moyo, Sylvester Rodgers
Globally, human immunodeficiency virus type 1 (HIV-1) is extraordinarily variable, and this diversity poses a major obstacle to AIDS vaccine development, diagnosis and therapy. Since HIV-1 M group began its expansion in humans roughly 70 years ago it has diversified rapidly now comprising a number of different subtypes and circulating recombinant forms (CRFs). Currently, strains belonging to the same subtype can differ by up to 20% in their envelope gene, and between subtype distances can soar to 35%. Moreover this diversity is continually growing. Although the scale of the HIV-1 pandemic makes action imperative, there is still much to learn about the extent and immunological implications of HIV-1 sequence diversity. As with other infectious agents, effective public health surveillance is essential to track the epidemic, guide research, and direct prevention activities. Significant challenges were highlighted by recent finding that some of the more divergent HIV-1 strains were not reliably detected by all antibody screening tests in current use. HIV-1 subtype C is responsible for the vast majority of the estimated 5 million infected South Africans. Thus, while subtype C viruses dominate the epidemic, the exceptional high prevalence rates in South Africa could provide significant opportunities for the spread of new genetic subtypes and/or evolution of current subtypes. Furthermore, analysis should therefore focus on areas where little information is known, such as the Limpopo Province, and where the opportunity for the introduction of new variants exists, and where prevalence rates are relatively high. The strategic location of the Province makes it imperative for regular diversity studies to be carried out. The implications of HIV-1 diversity in diagnostics and vaccine development; and the formulation of treatment regimens necessitated this study. Thus, this study therefore identified and characterized circulating HIV-1 genetic variants in sere-positive, drug na"fve populations from Limpopo Province where there is an estimated prevalence rate of about 19%. The molecular epidemiology of HIV-1 in two highly endemic areas in Limpopo Province of South Africa; mutations associated with drug resistance to protease inhibitors (Pis), nucleotide reverse transcriptase inhibitors (NRTls) and non nucleoside reverse transcriptase inhibitor (NNRTs), co-receptor usage and epitope mapping of HIV-1 isolates from drug naive individuals were investigated. Subtyping was done by phylogenetic analysis making use of ClustalX2 software while drug resistance mutation analysis, co-receptor usage prediction epitope mapping and substitution of the functional motifs were all determined by interpretation algorithms. Phylogenetic analysis of the test isolates revealed that subtype C is predominantly driving the epidemic in northern South Africa (Limpopo Province). Co-receptor usage prediction showed that majority of the isolates were R5 viruses as all had their tetrapeptide GPGQ motif characteristic of subtype C utilizing CCR5 viruses conserved. Genetic drug resistance mutation analysis of the 35 PR gene sequences did not reveal any major mutation associated with resistance but a high degree of minor mutations and polymorphisms were observed. Examination of the 44 RT genes showed a K103N substitution in two isolates. K103N change causes high level resistance to nevirapine. Epitope mapping of the gag p17 and p24 consensus sequences of the test isolates did not reveal any difference between them and the subtype C consensus sequences. They all had the same dissociation constant for the epitopes recognized by the HLA they were mapped against. Also, all the functional motifs in the PR and RT genes were conserved in majority of the test isolates. Molecular characterization of the test isolates has helped to update the baseline data on the circulating strains of HIV -1 in northern South Africa. Since all the isolates are subtype C as in other regions of South Africa and result of epitope mapping compares very well with those of subtype C consensus sequences, vaccine based on subtype C viruses could be designed and evaluated in the Province. Also, it has shown that entry inhibitor- the new class of antiretroviral drug could be of significance should the current NRTls and NNRTls begins to fail as majority of the isolates had their GPGQ motifs conserved. Since no important resistance mutation to the Pis and RTls was found among the test isolates, usage of these classes of drugs will continue to have positive impact in reducing morbidity and mortality due to AIDS in the studied area. The second element of this study focused on the amplification and analysis of a unique recombinant form composed of subtypes A1 and C subgenomic regions. Recombination plays a key role in HIV-1 genetic diversity which on the long run has a grave implication on diagnosis, therapy and vaccine development. The URF recombinant that was analysed was isolated from a female patient residing at Bela Bela which has a high HIV-1 prevalence. The amplified near-full length genome was sequenced by the 454 Genome Sequencer FLX system. The sequence generated was delineated into respective gene by the sequence locator- a web based online tool. Analysis of the recombinant virus was carried out in order to determine the subtypes that constituted the mosaic genome making use of jpHMM and REGA subtyping analytical tools. The results obtained revealed that the mosaic genome is composed of A1/C with seven breakpoints of recombination partitioning the genome into eight segments alternating between sub-subtypes A1 and C viruses. Analysis of the near-full length genome by subtyping tools showed discordant assignment of some gene regions by the different tools. Further analysis of the accessory genes did not reveal any major changes like premature termination or loss of functional motifs but deletions and insertions were observed in the tat, rev and net genes respectively. The isolation of a recombinant virus in a region where subtype C is the dominant variant shows the dynamic nature of this virus and calls for regular monitoring of the HIV-1 genetic landscape of the region. The third component of this study also involved the analysis of a recombinant virus isolated from a female patient at Mankweng Hospital near Polokwane the provincial capital of Limpopo Province. Partial fragment of 5665 nucleotides was generated, sequenced and analysed by various subtype analytical tools. Presence of drug resistance mutations in the PR, RT and IN genes was determined as well as prediction of co-receptor usage. Results revealed a mosaic recombination between subtype C and CRF11_cpx only at the RT gene of the isolate. All other gene regions analysed phylogenetically belong to pure subtype C virus. This is a novel strain as there is no known variant that has this genomic recombination in the HIV database. The epidemiological implication of this strain in Limpopo Province is not known. The frequency and pattern of polymorphisms among HIV-1 subtypes associated with resistance or resulting to a faster emergence of drug resistance once under drug pressure has been evaluated extensively on subtype B and little information exist about other subtypes. Subtype C variants are responsible for more than 50% of the global epidemic, and it is the subtype that is driving the epidemic in Southern Africa, the region with the highest HIV prevalence in the world. Antiretroviral scale up in the Limpopo region is high and therefore, it is necessary to determine whether genetic subtype differences will influence therapy outcome. The investigative theme of chapter five of this thesis is on the implications of nucleotide polymorphisms on the genetic barrier to evolution of drug resistance mutations in subtype C viruses when compared to the global subtype B consensus sequence. The protease and reverse transcriptase nucleotide sequences generated in this study were compared with the global subtype B consensus sequence at codons known to code for drug resistance mutations according to the Stanford drug resistance algorithm. The results revealed a reduced genetic barrier in subtype C viruses at codon V106M (GTA to GTG) and an increased barrier at codon L21OW (TTA/CTG/CTA to TGG) when compared to subtype B global consensus sequence. From this analysis, these are the only codons where significant differences exist between the subtypes. Apparently, there are, no major genetic barriers existing between subtypes B and C at known positions that code for drug resistance mutations. In conclusion, HIV-1 subtype C viruses is the predominant circulating variant in Limpopo Province as phylogenetic analyses of the partial gag, pol, and env C2- C3 gene fragments from HIV chronically infected patients showed that majority of the viruses are HIV-1 subtype C. The circulating HIV-1 viruses will be susceptible to the currently available protease inhibitors and reverse transcriptase inhibitors as drug resistance mutations in the naive population are very low (4.7%). Two unique recombinant forms HIV-1 A1/C and HIV-1 C/CRF11_cpx were each detected from two different individuals in the Waterberg and Capricorn districts respectively. There is no immunological difference between the HIV-1 subtype C viruses from Limpopo Province and the global consensus of subtype C viruses as epitope mapping using the consensus generated from test isolates had the same dissociation constant as the subtype C consensus sequence. Also, there is apparently no significant difference on the impact of nucleotide polymorphisms on the genetic barrier to antiretroviral drug resistance between subtype C viruses and subtype B viruses.
Open Access
Mathematical modelling of transmission and control of malaria
(2012-12-19) Mulaudzi, Matodzi Stanley; Garira, Winston
Malaria starts with plasmodium sporozoites infection of the host liver, where development into blood stage parasites occurs. A number of deterministic models are developed in this thesis. The release of modified mosquitoes aims to displace gradually the wild (natural) mosquito from the habitat. We discuss the suitability of this technique when applied to pre-domestically adapted plasmodium falciparum mosquitoes which are transmissor of malaria disease. The dynamics of interaction of sporozoites, liver cells, merozoites and red blood cells which cause the symptoms and pathology of the disease is comprehensively studied. We then show how variability of host-parasite immunity is incorporated in the model which are constructed to include liver and blood compartments by subdividing the host population into various mutually exclusive compartments. The increase in eggs, larval and pupal stages of mosquitoes increase the vector mosquito population and transmission of the disease, hence the suggestion that immature and adult mosquitoes be controlled extensively. The models which are in the form of nonlinear ordinary differential equations are rigorously analysed using ex tensively analytic and numerical techniques to determine important epidemiological thresholds, stability of the steady states and the persistence of infection in the respective populations. Conclusions are made based on the results obtained from the analysis of the models of malaria that have been developed
Open Access
How fast can you climb a mountain? climate change, ant assemblages and a centre of endemism
(2012-12-19) Munyai, Thinandavha Caswell; Foord, S. H.; Baxter, R. M.
Metadata only
Computational study of the molecules of selected acylated phloroglucinols in vacuo and in solution
(2012-12-19) Kabanda, Mwombeki Mwadham; Mammino, Liliana; Ghio, Caterina
This thesis is concerned with the computational study of acylphloroglucinols - a class of derivatives of phloroglucinol characterised by the presence of a COR group - using electronic structure methods. The compounds of this class are known to be biologically active and this is the reason for the interest in their study. A preliminary investigation was conducted on the parent molecule (phloroglucinol), calculating it in vacuo and in solution and comparing it with the other hydroxybenzenes. The aim was to identify relevant characteristics, so as to be able to verify whether and to what extent these characteristics are carried on to acylphloroglucinols and maintain stabilizing influences for the whole class of compounds. The mutual orientation of the phenolic OH groups is one of these characteristics. A systematic conformational study was performed on over 140 different acylphloroglucinol structures (both model and actual), in vacuo and in three solvents differing by polarity and hydrogen bonding abilities: chloroform, acetonitrile and water. The study in water solution was complemented by the study of adducts with explicit water molecules. The results show that the most stabilising factor in all the media and for all the structures is the intramolecular hydrogen bond engaging the sp2 0 of the COR group and one of the phenolic OH ortho to it; hence, particular attention was devoted to the study of the characteristics (parameters and energy) of this hydrogen bond. The results in solution show the influence of the solvent on the molecular structures (including the characteristics of the intramolecular hydrogen bond) and the energy aspects of the solution process. The results of the study of adducts with explicit water molecules show possible preferred arrangements of water molecules around the studied acylphloroglucinol molecule, up to approximating the first solvation layer, and facilitate the interpretation of the results in water solution. Different computational methods (HF, MP2 and OFT were utilised, also depending on affordability considerations for structures of different sizes), so as to be able to compare their results and to obtain an assessment of the performance of less expensive methods (like HF), in view of their utilisation for larger acylphloroglucinol structures for which more sophisticated methods (like MP2) remain unaffordable. Comparisons show interesting similarity in the identification of trends for the most important aspects.
Open Access
A comparative evaluation of rural development programmes in the Thulamela Municipality : a case study of Sidou and Malavuwe Villages
(2013) Musiwalo, Takalani Enos; Nelwamondo, T. M.; Mudau, N. V.
The focus of the study is on the comparative assessment of Rural Development Programmes between Sidou and Malavuwe Village within Ward 22 of the Thulamela Municipality. The study aims to investigate the gap that exists between effective programme implementation and less effective programme implementation in rural areas. To achieve this, the study uses Malavuwe Village as a control village and Sidou Village as an experiment village. The study found that there was a discrepancy in service delivery between the two villages; more services were delivered effectively at Malavuwe than at Sidou Village. The study further investigates the causes of this discrepancy in service delivery between the two villages and also suggests feasible approaches that can be employed by the Thulamela Municipality to enhance programme implementation and service delivery within the study area. The study found that Sidou Village lacked community services such as clinics, high schools, community halls, sporting facilities and income generating community projects. On the contrary, Malavuwe Village had most community services. Based on the findings of the study, it is recommended that the Thulamela Municipality should ensure thorough provision of services and encourage community participation through consultation and partnership at Sidou Village. Such an approach will be bottom-up and will encourage community members at Sidou Village to be actively involved in the prioritisation and implementation of vital services, thus raising the socioeconomic conditions and infrastructure development in the village
Open Access
Population biology of Elaeodendron transvaalense Jacq. in the presence of harvesting
(Fyton, 2013-01-12) Tshisikhawe, M. P.; Van Rooyen, M. W.
Elaeodendron transvaalense Jacq. is one of the medicinal plant species commonly used by people in the Venda region. The species is known to treat a variety of diseases. It is widely used and important to traditional healers. Because of this, it found its way into the muthi markets, and it is among the seven most commonly traded plant species in the Venda region. This study investigated the impact of bark harvesting on the population structure of this species. The study revealed that although the level of bark harvesting is high, the species is able to resist that stress since it is a fine-grained species. The population also showed the ability to regenerate as it exhibited an inverse J-shaped curve. The crown health status was generally good although some individuals, contributing 9% of the sample, had dead crowns, which are a cause for concern. A linear relationship was noticed between areas harvested and stem circumference, which is understandable considering the large surface area of harvestable bark on bigger individuals.

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